1. Field of the Invention
The present invention relates to electromagnetic relays, and in particular to electromagnetic relays having an elongated armature extending substantially parallel to the axis of the excitation coil and to which at least one contact element is connected at one side thereof via an insulating element so as to be substantially parallel to the armature and having a free end for making and breaking with at least one cooperating stationary contact element.
2. Related Application
This application is related to the application of R. -D. Kimpel, U. Rauterberg and H. Tamm filed simultaneously herewith entitled "Polarized Electromagnetic Relay" and assigned Ser. No. 401,235.
3. Description of the Prior Art
A relay is described in British Pat. No. 1,258,862 having a coil body with a plurality of center contact springs disposed in a plane which are clamped by means of a resilient retaining clamp to a plate-like armature. The contact springs are electrically insulated from the armature by an intervening insulating foil. The contact springs thus simultaneously form the bearing for the armature which, upon excitation of the relay, bridges two yoke core elements disposed at a distance from the armature. The flat side of the armature is disposed opposite the spring contacts. A separate actuation plunger is eliminated in this conventional structure by means of the direct connection of the contact springs with the armature. Because of the elimination of the conventional plunger, the friction caused by such a plunger which is injurious to the contacts is not present.
The above-described conventional structure has the disadvantage, however, that not only the armature and the core, but also all center contact springs are disposed inside the coil body, thereby requiring a coil with a relatively large diameter. As a result of the position of the armature and the permanently connected center contact springs with respect to the cooperating stationary contacts, a relatively short spring length is necessary thereby resulting in significant stressing of the material comprising the spring contact elements, thereby contributing to a shortened relay useful life. Moreover, the positioning of the movable contact springs directly at one side of the flat armature has the disadvantage that the armature can form a working air gap only at the one flat side thereof which is opposite the contact springs so that the relay is not suitable for use with a polarized magnetic system in which the armature forms working air gaps with two opposite pole plates for movement therebetween.